1. Field of the Disclosure
The invention generally relates to the cooling of converter arrangements for light sources with high luminance, in particular for high-power projectors.
2. Description of Related Art
Converter arrangements are used in conjunction with light sources, in order to change the wave length of and to re-emit the light emitted by a primary light source and impinging on the converter arrangement. This way, a light source is formed. For that purpose, the surface of the converter arrangement is for example at least partially equipped with a fluorescent material.
U.S. application No. 2009/034284 for example describes an illumination device generating light by a rotating wheel furnished with a fluorescent material and excited by radiation from a solid-state light source. The purpose of the invention described in U.S. application No. 2009/034284 is to generate various colour channels being clocked in time, by segmenting the wheel with different phosphors.
JP application No. 2012 037681 discloses the application of this principle in detail.
DE 10 2011 084 961 also describes a segmented fluorescent material wheel. Ceramic phosphor segments are used, wherein these segments may be metallised and connected with the carrying wheel by means of soldering to achieve a good thermal connection of the segments with the carrying wheel.
In these three aforementioned documents, the carrying wheel is described as a flat circular disk. According to DE 10 2011 084 961, such a flat circular disk may also have recesses or embossments for receiving the segments.
DE 10 2012 005 654 of the applicant describes a converter wheel with a venting function, for example by means of additional lamellae, to improve cooling of the converter wheel.
According to applicant's application DE 10 2010 034 054, it is particularly advantageous, if the conversion disk is self-cooling. This may for example be achieved by a winged wheel on the rotational axis of the phosphor carrier, forming a so-called radial fan. By the rotation, an airflow is generated which dissipates the heat to the environment.
Generally, excessive temperatures at the converter may generally lead to an accelerated degradation of the converter material and also of the connection to the carrier of the converter. Further, heating-up of the converter may result in a decrease of the conversion efficiency and/or a change in colour of the emitted secondary or fluorescent light.
Against this background, it is an object of the invention to provide a converter arrangement which ensures a particularly efficient cooling of the fluorescent material and thereby generates particularly high luminances, as well as to improve the long-term stability of the arrangement.